Chapter 14, Problem 14.42P

Interpretation Introduction

Interpretation:

The given molecules are to be ranked in order of increasing exothermic heat of hydrogenation.

Concept introduction:

The heat of hydrogenation is the amount of energy released when a hydrogen molecule is added to a double or triple bond. It is based on the stability of $\text{π}$ systems. Greater the conjugation, stable is the molecule and has less exothermic heat of hydrogenation. Aromatic molecules are more stable compared to nonaromatic compounds. Aromatic molecule has less heat of hydrogenation than the nonaromatic compound having conjugation with the same number of $\text{π}$ electrons.